Market adoption of wireless LAN (WLAN) technology has exploded, as users from a wide range of backgrounds and vertical industries have brought this technology into their homes, offices, and increasingly into the public air space. This inflection point has highlighted not only the limitations of earlier-generation systems, but also the changing role that WLAN technology now plays in people's work and lifestyles across the globe. Indeed, WLANs are rapidly changing from convenience networks to business-critical networks. Increasingly users are depending on WLANs to improve the timeliness and productivity of their communications and applications, and in doing so, require greater visibility, security, management, and performance from their network.
In wireless networks, the Media Access Control (MAC) protocol of the IEEE 802.11 standard utilizes positive acknowledgements and a collision avoidance scheme to achieve high reliability at the link layer. However, these measures also introduce overhead at the MAC layer. The IEEE 802.11a/b/g physical layer (PHY) introduces additional overhead, such as preambles, forward error correction (FEC), etc. In general, the smaller the data packet size is, the lower the MAC/PHY efficiency is. Most internet packets are small packets. In a mesh network, data packets typically need to traverse multiple hops before reaching the final destination; and the mesh backhaul has to carry traffic from many WLANs. In addition to MAC/PHY overhead, mesh-related headers introduce additional overhead. IEEE 802.11n defines packet aggregation schemes in a WLAN environment, e.g., Media Access Control Service Data Unit aggregation (A-MSDU) and aggregate MAC Protocol Data Unit aggregation (A-MPDU). An A-MSDU is composed of more than one MSDU, while an A-MPDU is composed of more than one MPDU. Both of these aggregation schemes seek to improve MAC/PHY efficiency by aggregating small packets together. Because IEEE 802.11n is designed to operate in one-hop WLANs, these two schemes only aggregate packets intended for the same immediate receiver. Directly adopting IEEE 802.11n's packet aggregating schemes means small packets are assembled and de-assembled at each hop even though they may have the same ultimate destination.